Aristide Economopoulos/The Star-LedgerDEP Commissioner Bob Martin listens to Gov. Christie during the press conference in Liberty State Park in Jersey City today. Gov. Chris Christie announced plans to revamp state parks and historic sites

JERSEY CITY — Gov. Chris Christie today unveiled a plan to shore up the state’s parks — considered some of the crown jewels of the Garden State — which face the risk of being shuttered or sold every year because they cost far more money than they raise.

With Liberty State Park as his backdrop, the governor said at a news conference that he planned to privatize and expand such amenities as concession stands, canoe rental operations and lifeguard stands at the parks, though they would remain under state control.

The governor said he would keep entrance fees and parking costs the same for New Jersey residents, but raise them for out-of-state visitors. However, he said that beginning next year he plans to increase fees for activities such as camping and putting on large events.

"The more we can lessen their dependence on general operating funds and have them generating their own funds to sustain them, the better off we’re going to be as a state," Christie said.

To be sure, courting private money for public parks is not a new concept. Officials at the federal level and in some New Jersey counties have resorted to similar measures as a way to avoid closing the gates at popular destinations without relinquishing control.

But the changes often worry environmentalists, who fear they are a slippery slope toward making parks less affordable for the average resident, or, worse yet, toward selling them altogether.

"When a for-profit company takes over public infrastructure, public lands, and is responsible for public health and safety, we are concerned that their mission, which is private and corporate, does not include anything for the public," said Jeff Tittel, head of the New Jersey Sierra Club.

Under Christie’s plan, to be rolled out over the next four years, the state will maintain ownership of its more than three dozen parks, but by farming out many concessions and services, it will allow the shrinking maintenance crews and police forces to focus on keeping the parks clean and safe.

At the same time, he said no workers would lose their jobs as a result of the changes.

Aside from seeking sponsors, Christie also plans to offer some of the 440,000 acres of state land for companies to build arrays of solar panels, and to open some of the most scenic state buildings as vacation rentals.

"This is about the tough choices that need to be made from a fiscal perspective without having to sacrifice some of the real opportunities that make New Jersey such a special place," he said.

He said many other states have scaled back services or closed locations to save money.

The state parks cost about $39 million annually to operate and maintain but raise only about $8 million, Christie said, putting them at risk at budget time.

His plan calls for almost doubling the revenue from the parks by 2015, and that the money would go right back into them.

A list of possible fee increases for next year has not been released.

Since 2000, supervisory staffing at New Jersey’s parks has decreased 41 percent and the number of maintenance workers has fallen 30 percent. At the same time, the state is responsible for 153,000 more acres than it was a decade ago, and a record 18 million people are expected to visit the parks this year.

Bob Martin, commissioner of the state Department of Environmental Protection, which oversees the parks, said the public would enjoy the same access as always to the outdoor destinations.

He also said the state would not sell "naming rights" for the parks.

"We’d like companies to help sponsor things in the park, provide money for the parks, invest in the parks long term," Martin said after today’s new conference.

For example, he said he would encourage corporations to build new boat ramps, fishing areas and swimming areas, and pay for their operation.

Martin said his department has already had preliminary talks with some companies, and has issued a request for proposals to sell food at Liberty State Park.